Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming, and ultimately very expensive endeavors. As a result, over the years, a significant amount of added emphasis has been placed on well monitoring and maintenance. Furthermore, perhaps even more emphasis has been directed at initial well architecture and design. All in all, careful attention to design, monitoring and maintenance may help maximize production and extend well life. Thus, a substantial return on the investment in the completed well may be better ensured.
In the case of well monitoring and logging, mostly minimally-invasive applications may be utilized which provide temperature, pressure and other production related information. By contrast, well design, completion and subsequent maintenance, may involve a host of more direct interventional applications. For example, sliding sleeves incorporated into a casing defining the well may be shifted open or closed to regulate production. Additionally, high pressure perforating and stimulating applications may be run at certain downhole well locations. Indeed, such applications may be preceded by the additional intervention of closing off and isolating the downhole locations with a bridge plug or mechanical packer capable of accommodating such high pressure applications. A host of other interventional applications may similarly be directed at downhole well regions.
In certain circumstances, attempts have been made to combine different application tools on a single delivery line. So, for example, a wireline cable may be used to deliver a logging tool coupled to a sleeve shifting tool such that both logging and sleeve shifting may be achieved with a single deployment into the well. Thus, several hours, if not days, are saved in avoiding the need for multiple deployments of tools into the well. However, it is worth noting that in such a circumstance, the interventional, sleeve shifting, tool is combined with a more passive tool which does not require its own large drive assembly.
In some circumstances, a more actively interventional tool, such as a plug setting tool or an anchoring tool, may be combined with the noted sleeve shifting tool. For example, anchoring and sleeve shifting actuation may serve to aid in advancement of the setting tool to a targeted location in the well for bridge plug deployment. In this manner, larger scale tractoring operations may be avoided in the circumstance of a vertical well that is prone to present certain downhole obstacles (e.g. hydrostatic sticking).
In this example scenario of combined anchoring, sleeve shifting, and plug setting tools incorporated into the same downhole system, each tool is equipped with its own independent drive assembly. Indeed, for these particular interventional actuator tools, each drive assembly would include a dedicated electronics module and a hydraulic power unit housing its own pump and motor.
Unfortunately, providing each tool with its own independent electric-hydraulic drive assembly on a single downhole system presents a whole new set of challenges and drawbacks, not the least of which is tripling drive assembly costs due to the utilization of three separate, independently driven, tools. For example, in the circumstance of a controlled pressure cased well, a riser, generally about 60 feet high, may be positioned at the well head to help regulate and maintain pressure. This limits the overall length of the downhole system that may be attached to the wireline cable (e.g. no more than about 60 feet in the example scenario). Thus, in a likely circumstance where each drive assembly and associated tool exceed about 25 combined feet, the overall system, 75 feet in length, would be unavailable for deployment in the well.
Other concerns beyond size and expense of such a combined system of different tools and assemblies also persist. For example, the inclusion of multiple electronics modules means that multiple electronic boards are utilized. Thus, the odds of electronic board failure on any given run in the well with the system are inherently driven up. Ultimately, on the whole, combined active interventional tools on the same downhole system are generally avoided due to practical concerns over size, expense, and reliability.